Development of an integrated approach to using ionic liquids for terpene recovery from loblolly pine

Loblolly pine (Pinus taeda L.) is widely used as a feedstock in the pulp and paper industry. In addition, oleoresin present in wood represents a unique source of potential drop-in fuel molecules, particularly in the form of monoterpenes such as pinene. In the context of forest biorefineries, terpene extraction unit operations must be integrated with the overall conversion process. Terpenes in pine wood, which play a role in plant defense mechanisms, are not efficiently recovered unless an external factor disrupts the microstructure and the cell integrity by cracking the cellulose fibers. The well-known solvating power of certain ionic liquids (ILs), such as 1-ethyl-3-methylimidazolium acetate, can disrupt the intricate network between polymer constituents in the wood, and efficiently extract terpenes from these tissues. To better exploit these results, we investigated the utilization of ILs in connection with different analytical approaches and protocols such as solid-liquid extraction, distillation, and headspace, using GC–MS to quantitatively optimize extraction of these high value fuel molecules. We sought to develop an IL-based method for efficient extraction of terpenes from pine that can be a compelling alternative to current conventional routes (tree tapping, pulp mill, solvent-based steam extraction) that can be easily integrated within the biorefinery model where sugars, extractives (terpenes), and lignin valorization are all essential unit operations of biomass conversion.